The subject of water hardness (or softness) is often very confusing and people tend to shy away from trying to understand it. We will try to go through it as simply as possible to help you understand the topic.
Let’s face it, we’re trying to keep tropical fish here, not earn ourselves a degree in science!
Water hardness will differ from source to source and you may wish to choose your fish to suite the water in your area. Yes, as with PH, fish are suited to different levels of hardness and can be divided into categories, which we will go through later.
In the long run you will save yourself some hassle, but at the same time you shouldn’t forget that your water supply can change without notice.
Keep your test kit handy!
For those who really want to know, these materials consist mainly of calcium and magnesium ions, bicarbonates and sulfates. Their common sources are limestone, chalk, dolomite and other solid materials that the water has come into contact with before it reaches our taps.
Most people will know if the water is generally hard in their area. You can tell this if you gets lots of scaling left behind in your kettle or around your water taps at home.
Hard water can be broken up into 2 categories; Carbonate Hardness (KH) and General Hardness (GH).
Calcium Carbonate is removed from water during boiling. An example of this can be seen above when we spoke about scale residue being left inside your kettle. After the water has cooled down it will be noticeably softer.
Another name for this is ‘Permanent Hardness’, but I don’t think the name really fits. While these elements cannot be removed by boiling the water, there are other ways to remove them. This means it’s not really permanent.
They talk about degrees of hardness. This would be written as °kH or °gH. The problem comes in where different you get German degrees, American degrees, English degrees and even French degrees.
Now they may all be in degrees, but the formulas used to work them out are not the same. Some of them may be very similar though.
The measurement for water hardness I prefer is Parts Per Million (ppm) . It’s much easier to understand and basically means milligrams of calcium carbonate per litre of water. This seems to be the most popular way of measuring hardness as is widely used.
Is it really necessary? If you are having problems with your fish, then this may be something you want to look into.Adjusting the KH (carbonate hardness) can lower your fish tanks resistance to changes in the PH. You must be willing to monitor this.You should also remember that while most fish will have a recommended hardness range, many of them can survive in most conditions. Some are just more resistant than others and some have adapted over time through being bred in aquariums.
You can also buy hardening treatments from your pet store to increase hardness. Always read the instructions on the packaging and use together with your test kit.
It is important to only make small changes at a time. Drastic changes can harm your fish and even kill them. Your small water changes should also be happening at very regular intervals, this will help you keep the balance in your aquarium.
As with increasing hardness, there are also a number of ways to decrease hardness. These range from reasonable cheap and easy methods to buying expensive equipment to do the job.
One method is to dilute hard water with soft water from another source. The trick here is getting the soft water! Some people use deionized water or distilled water to dilute their tap water and bring the hardness levels down.
You may want to look into using a reverse osmosis water filter. Although this process is the one I was referring to as being expensive and should probably be left to the enthusiasts with a few years of experience under their belt.
Then we have the boiling method to remove the temporary or carbonate hardness (KH). While many people will jump at this idea, we must remember that a low KH can cause PH problems. Boiled water will also need to be aerated extensively before being put into the aquarium. Boiling the water removes all the oxygen from inside it.
Now we come to my recommended method, the water softener pillow . These pillows are readily available and are quite simple to use. They contain a resin which chemically absorbs the hardness out of the water. The resin can only hold a certain amount of hardness, so they need to be changed or cleaned. You will need to read the instructions on the packaging for your product to find out exactly how to use it.
Wikipedia has a good page on Hard Water if you really want to know about the in-depth terms and technical details.(page opens in a new window)
Always make small changes! Whether it be raising or dropping hardness, or doing water changes. You don’t want to shock your fish. Keep your water testing kit handy!